This invention is an improvement in known methods of setting or resetting poles in the ground, ground line protection of poles or encapsulation of pole treatment chemicals and enhancement of the strength to density ratio, of rigid foam polyurethane resins formed in-situ. The improvement resides in the use of compositions having electrical conductivity. The resulting electrical contact surface area of the pole to the earth is greatly enhanced relative to conventional grounding techniques.
The present invention is an improvement in the technology disclosed in U.S. Pat. Nos. 3,968,657 to Hannay, 5,466,094 to Kirby et al., 3,564,859 to Goodman, 3,403,520 to Goodman, and 4,966,497 to Kirby which describe related methods for resetting poles with foam plastic. The entire disclosures of U.S. Pat. Nos. 3,968,657, 3,564,859, 3,403,520, 4,966,497, and 5,466,094 are incorporated by reference as though fully set out herein.
In brief, U.S. Pat. No. 3,403,520 describes a method of setting pole forms in the ground by making a hole which is only slightly larger than the butt of the pole to be placed in the hole, placing the pole in the hole in the desired position, partially filling the hole with a reactive component mixture with a synthetic resin and a blowing agent and permitting the reaction to complete so as to expand the resinous foam into all the space between the pole and the sides of the hole. The expanded resinous foam adheres to and seals the surface of the embedded section of the pole protecting it from moisture, chemicals and rodents and sets the pole in the hole. The expanding resinous foam fills all the voids, surfaces, crevices and notches in the sides and bottom of the hole.
U.S. Pat. No. 3,564,859 describes a procedure for straightening and refilling the hole. It utilizes the same method as U.S. Pat. No. 3,403,520 for producing foam and for filling voids resulting when an existing installed pole has been realigned after it has been canted or tilted.
U.S. Pat. No. 3,968,657 was an improvement upon the in-situ reaction chemistry used to prepare the backfill material. The '657 patent disclosed the addition of a non-volatile water-immiscible material to the mixture so that properties of the resultant product are not affected excessively in the presence of groundwater.
A further improvement in the backfill-forming chemistry was described in U.S. Pat. No. 4,966,497. The '497 patent describes a procedure that is an improvement on the above methods because halogenated hydrocarbon blowing agents, more particularly chlorofluorocarbons, are not required. Further, the composition decreased the cost per unit of the polyurethane foam.
U.S. Pat. No. 5,466,094 represented another improvement pole setting or resetting compositions and methods. In the '094 patent, the polyurethane forming chemistry was modified by stabilizing the highly reactive isocyanate component by pre-reaction to form a prepolymer.
All of the aforementioned patents are devoid of any teaching which describes a backfill composition or method which simultaneously sets or resets the pole and aids in the electrical grounding of the pole. A good ground connection effectively directs the excessive current from a lightening strike to the ground. Proper grounding also helps to insure the quality of the power being transmitted by helping to eliminate or minimize voltage spikes and interference such as RF signals from adversely affecting sensitive electronic equipment.
Grounding is an important “safety valve” of an electrical system, protecting both the system and persons working on the system. Proper grounding is important for a number of reasons. All electrical equipment requires grounding because of possible short circuits within the system. Electrical sensors, such as relays require a reference, which is oftentimes ground. Harmonics created by semiconductor equipment and unbalanced loads depend upon good ground to stabilize the system. The standard AC system in the U.S. operates at 60 cycles/second (Hz). Harmonics are additional cycles superimposed on the 60 Hz cycle curve. The total load comprises the basic sine wave of the expected system load plus the harmonics generated, resulting in a much larger total than the expected load. Harmonics are oftentimes caused by unbalanced loads; such as produced by single phase motors, temporary faults on the line or equipment and by the use of semiconductors, etc. Harmonics can be eliminated by directing them to the ground on a grounded “Y” of a “Y”-Delta connection at the transformer bank. This requires a strong ground at the transformer bank. As earlier mentioned, good ground is helpful when lightening strikes a utility pole. The speed of discharging a lightening strike minimizes damages to system components. Lightening strikes can be in excess of 5000 amps, therefore a strong ground is essential to accommodate such high currents. The present invention is applicable to any and all of the aforementioned problems. Although various polymer backfill materials are preferred, the method improves the grounding performance of a wide variety of polymer backfill materials useful pole setting and/or resetting agents.
The present invention simultaneously improves the stability and grounding of modern electrical transmission lines and other utility poles. Electrical systems use the crust of the earth as part of the return conductor. The grounded, system neutral protects the phase conductors from excessive amperage and voltage as well as to help balance phase voltage and harmonics. Continuously grounded “static” shield wire's purpose is to get the excessive current of a lightening strike into the ground as soon as possible to avoid damage to the shielding conductors. Good grounding is particularly important today with the sophisticated electronic equipment currently widespread. Additionally, good grounding helps to minimize service interruptions. The need for good backfill materials to set and reset transmission line poles has been known for quite some time and good progress has been made in this area. By making any of the currently used backfill materials conductive, the surface area “connected” to the earth can be greatly enhanced.
For instance, the conventional method of connecting to the earth is a ⅝ths inch×10 foot ground rod driven into the earth. This method has a surface area of 235 in2. A 10 inch×10 inch copper plate has a surface area of 100 in2. A butt wrap ground of No. 6 copper wire, 20 feet long, wrapped around the pole will give a surface area of 75 in2. This is compared to the surface area of a backfill, which is an approximately 20 inch diameter hole, 6 feet deep, giving a surface area in contact with the earth of up to 4500 in2 which is 19 and 60 times bigger respectively. Therefore, the electrical contact with the ground is increased. This is important in the areas of poor soil conductivity. As was discussed in the background section above, U.S. Pat. No. 4,966,497 teaches the use of using a modified urethane as a pole backfill material. By expanding the physical properties of this backfill material to include electrically conductive capabilities, the surface area and abilities of the grounding are vastly improved to include electrical ground in addition to physical grounding.